you can go here if you want to see what I did the hard way...this is a different thread for the same issue, this topic goes over a lot of possibilities. (
http://www.lucasforums.com/showthread.php?threadid=40696)
Or you can just try and open the game through the game directory, open the .exe with the sp at the end. If that doesn't make sence, then go to the thread. Hope that helps you out a bit, I hope we get to the bottom of why this occurs, bye.